Method of fabricating X-ray mask and method of fabricating semiconductor device using the X-ray mask

Abstract

In fabricating an X-ray mask, a chromium oxide film serving as an etching stopper is formed on a diamond film serving as an X-ray transmitter. Then, a diamond layer serving as a first X-ray absorber is formed on the chromium oxide film. Thereafter, a tungsten layer serving as a second X-ray absorber is formed on the diamond layer. Consequently, the diamond layer and the tungsten layer form an X-ray absorber having a laminated structure. When the X-ray absorber has a laminated structure including substances having different compositions, the transmittance and the phase shift quantity of the overall X-ray absorber can be readily adjusted. Thus, a method of fabricating an X-ray mask providing improved resolution of the pattern of a semiconductor device or the like is obtained.

1. A method of fabricating an X-ray mask comprising:
 etching an X-ray transmitter at a surface of said X-ray transmitter to form a plurality of recesses extending from the surface and into said X-ray transmitter, leaving portions of the surface between respective parts of recesses; and 
 forming a laminated X-ray absorber on said surface of said X-ray transmitter, but not in said recesses, wherein said laminated X-ray absorber includes at least two layers having different compositions, wherein phase shift of X-rays transmitted through said X-ray absorber is in a range of 0.3π to 0.6π and transmittance of the X-rays transmitted through said X-ray absorber is in a range of 30% to 60% for X-rays having an average exposure wavelength longer than 0.3 nm and shorter than 0.7 nm. 
 
     
     
       2. The method of fabricating an X-ray mask according to  claim 1 , wherein
 said laminated X-ray absorber includes a first X-ray absorber opposite said X-ray transmitter and a second X-ray absorber in contact with said first X-ray absorber, 
 tungsten is employed as one of said first X-ray absorber and said second X-ray absorber, and 
 diamond is employed as the other of said first X-ray absorber and said second X-ray absorber. 
 
     
     
       3. The method of fabricating an X-ray mask according to  claim 1 , wherein
 said laminated X-ray absorber includes a first X-ray absorber on said X-ray transmitter and a second X-ray absorber on said first X-ray absorber, and 
 the method of fabricating an X-ray mask further comprises:
 forming an etching stopper film, stopping etching when etching said first X-ray absorber on said X-ray transmitter, and 
 forming said second X-ray absorber on said etching stopper film. 
 
 
     
     
       4. The method of fabricating an X-ray mask according to  claim 1 , wherein
 said laminated X-ray absorber includes a first X-ray absorber opposite said X-ray transmitter and a second X-ray absorber on said first X-ray absorber, and 
 the method of fabricating an X-ray mask further comprises:
 forming an interlayer film as an etching stopper or a hard mask on said first X-ray absorber, and 
 forming said second X-ray absorber on said interlayer film. 
 
 
     
     
       5. The method of fabricating an X-ray mask according to  claim 1 , wherein said laminated X-ray absorber has a layer containing at least one substance selected from the group consisting of lithium, beryllium, boron, carbon, sodium, magnesium, aluminum, silicon, phosphorus, sulfur, potassium, calcium, scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, gallium, germanium, arsenic, selenium, palladium, silver, cadmium, indium, tin, antimony, tellurium, cesium, barium, mixtures of these elements, a carbide including silicon carbide and tungsten carbide, a nitride including silicon nitride, aluminum nitride, and chromium nitride, an oxide including silicon oxide and chromium oxide, a fluoride, and an iodide. 
     
     
       6. The method of fabricating an X-ray mask according to  claim 1 , wherein said laminated X-ray absorber has a layer containing a substance selected from the group consisting of carbon, titanium, vanadium, chromium, manganese, iron, nickel, copper, zinc, gallium, germanium, arsenic, selenium, palladium, silver, cadmium, indium, tin, antimony, and tellurium. 
     
     
       7. The method of fabricating an X-ray mask according to  claim 1 , further comprising selectively implanting ions into regions of said X-ray transmitter where portions of said X-ray transmitter are to be removed in forming said recesses, before forming said recesses. 
     
     
       8. The method of fabricating an X-ray mask according to  claim 1 , including forming said laminated X-ray absorber in a periodic pattern. 
     
     
       9. A method of fabricating an X-ray mask comprising:
 forming an X-ray transmitter; 
 forming a first X-ray absorber opposite said X-ray transmitter, said first X-ray absorber including a plurality of spaced apart first X-ray absorber portions, each first X-ray absorber portion having side surfaces substantially transverse to said X-ray transmitter and a first width measured between the side surfaces of said first X-ray absorber portions; and 
 forming a second X-ray absorber on said first X-ray absorber, said second X-ray absorber comprising a plurality of second X-ray absorber portions spaced from each other, each second X-ray absorber portion being disposed on a corresponding one of the first X-ray absorber portions, each second X-ray absorber portion having side surfaces substantially transverse to said X-ray transmitter and a second width measured between the side surfaces of the second X-ray absorber portions, the second width being larger than the first width and none of the side surfaces of the second X-ray absorber portions being contiguous with the side surfaces of the first X-ray absorber portions. 
 
     
     
       10. The method of fabricating an X-ray mask according to  claim 9 , wherein at least one of said first and second X-ray absorbers is selected from the group consisting of lithium, beryllium, boron, carbon, sodium, magnesium, aluminum, silicon, phosphorus, sulfur, potassium, calcium, scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, gallium, germanium, arsenic, selenium, palladium, silver, cadmium, indium, tin, antimony, tellurium, cesium, barium, mixtures of these elements, a carbide including silicon carbide and tungsten carbide, a nitride including silicon nitride, aluminum nitride, and chromium nitride, an oxide including silicon oxide and chromium oxide, a fluoride, and an iodide. 
     
     
       11. The method of fabricating an X-ray mask according to  claim 9 , wherein at least one of said first and second X-ray absorbers is selected from the group consisting of carbon, titanium, vanadium, chromium, manganese, iron, nickel, copper, zinc, gallium, germanium, arsenic, selenium, palladium, silver, cadmium, indium, tin, antimony, and tellurium. 
     
     
       12. A method of fabricating a semiconductor device including carrying out an exposure with an X-ray mask having a geometric X-ray phase difference between the phase of X-rays transmitted through an X-ray transmission part of said X-ray mask and the phase of X-rays transmitted through an X-ray absorber of said X-ray mask in a range including 0.5π and proximity to 0.5π, between a resist film located at a position for forming an optical image with said X-rays and said X-ray mask, wherein
 said X-ray mask comprises an X-ray transmitter and said X-ray absorber includes a laminated structure having at least two layers on said X-ray transmitter, 
 said laminated structure includes at least two layers having different compositions, and 
 either the phase shift of the X-rays transmitted through said X-ray absorber is in a range of 0.3π to 0.6π or the transmittance of the X-rays transmitted through said X-ray absorber is in a range of 30% to 60%. 
 
     
     
       13. The method of fabricating a semiconductor device according to  claim 12 , including carrying out the exposure with an average exposure wavelength of the X-rays longer than 0.3 nm and shorter than 0.7 nm. 
     
     
       14. The method of fabricating a semiconductor device according to  claim 12 , wherein absolute value of difference between the geometric phase difference and the phase shift quantity is in a range including π and proximity to π. 
     
     
       15. A method of fabricating an X-ray mask comprising:
 forming an X-ray transmitter; 
 forming a first X-ray absorber opposite said X-ray transmitter, said first X-ray absorber including a plurality of spaced apart first X-ray absorber portions, each first X-ray absorber portion having a first width; and 
 forming a second X-ray absorber on said first X-ray absorber, said second X-ray absorber comprising a plurality of second X-ray absorber portions spaced from each other, each second X-ray absorber portion being disposed on a corresponding one of the first X-ray absorber portions, each second X-ray absorber portion having a second width, larger than the first width, wherein 
 tungsten is employed as one of said first and second X-ray absorbers, and 
 diamond is employed as the other of said first and second X-ray absorbers. 
 
     
     
       16. A method of fabricating an X-ray mask comprising:
 forming an X-ray transmitter; 
 forming a first X-ray absorber opposite said X-ray transmitter; 
 forming an etching stopper film, stopping etching when etching said first X-ray absorber on said X-ray transmitter, said first X-ray absorber including a plurality of spaced apart first X-ray absorber portions, each first X-ray absorber portion having a first width; and 
 forming a second X-ray absorber on said etching stopper film on said first X-ray absorber, said second X-ray absorber comprising a plurality of second X-ray absorber portions spaced from each other, each second X-ray absorber portion being disposed on a corresponding one of the first X-ray absorber portions, each second X-ray absorber portion having a second width, larger than the first width. 
 
     
     
       17. A method of fabricating an X-ray mask comprising:
 forming an X-ray transmitter; 
 forming a first X-ray absorber opposite said X-ray transmitter; 
 forming an interlayer film as an etching stopper or a hard mask on said first X-ray absorber, said first X-ray absorber including a plurality of spaced apart first X-ray absorber portions, each first X-ray absorber portion having a first width; and 
 forming a second X-ray absorber on said interlayer film on said first X-ray absorber, said second X-ray absorber comprising a plurality of second X-ray absorber portions spaced from each other, each second X-ray absorber portion being disposed on a corresponding one of the first X-ray absorber portions, each second X-ray absorber portion having a second width, larger than the first width. 
 
     
     
       18. A method of fabricating an X-ray mask comprising:
 forming an X-ray transmitter; 
 forming a first X-ray absorber of a first X-ray absorbing material opposite said X-ray transmitter, said first X-ray absorber including a plurality of spaced apart first X-ray absorber portions, each first X-ray absorber portion having a first width; and 
 forming a second X-ray absorber of a second X-ray absorbing material, different from said first X-ray absorbing material, on said first X-ray absorber, said second X-ray absorber comprising a plurality of second X-ray absorber portions spaced from each other, each second X-ray absorber portion being disposed on a corresponding one of the first X-ray absorber portions, each second X-ray absorber portion having a second width, larger than the first width.